Friend refuses to speak on the phone (1.5 years)

Ive been friends with someone for around 4 years now. A combination of in-person hangouts, calls, texts and lots of meme sharing on instagram.

In that period we both relocated to other places but we kept in touch.

At this moment we are talking (through text) about meeting up in a very concrete way. (Dates are locked in, activities picked out etc)

To cut to the chase:

Parallel to us talking a few times a week through text, I have been asking for us to speak on the phone as I believe that a friendship cannot just survive on pure texting. (And I need some specific input for the trip I am planning)

The pattern that arises is the exact every time:

Me: We should speak on the phone, are you free on Thursday?
She: Yes I am
Me on Wednesday evening: Let me know what a good time is tomorrow..
She: Remains silent

In stead she then diverts to instagram starts sending memes that she knows will trigger a reply from me and uses that to continue a conversation

Only when she feels (this is how I perceive it) will she move back to text.

Fast forward to this week... and the same pattern happened again but I called her out on it where I asked her why she is making this such an awkward topic? I speak to all of my close friends on the phone.. and I have not spoken to hear, heard her voice in 1,5 years.. that is NOT normal.

First days of silence, then an awkward reply that I think was meant to be funny about how she is always working (not true) and then she is tired so when she wants to speak I am usually already asleep...

..

Im old enough and mature enough to realize that I will not be spending time, money and precious vacation days to go cross country to visit her.. but what is this behavior?

If she just wants a 100% text based friendship, she can just say so?

I think I am just a distraction for her, someone to keep her busy and entertained. Speaking on the phone make it ""too real''?